let s = Symbol(); // 独一无二的
let s2 = Symbol();
console.log(s == s2);

let obj = {
    a: 1,
    [Symbol()]: function (arg) {
        console.log('------');
    },
    [Symbol()]: function (arg) {
        console.log('++++++');
    }
}
// console.log(obj);
for(let key in obj) {
    console.log(key);
}
console.log(Object.keys(obj));
console.log(
    Object.getOwnPropertyNames(obj)
);

Object.getOwnPropertySymbols(obj)
    .forEach(item => {
        obj[item]();
    })



// obj.a
// console.log(obj[s]());